Petroleum coke calcining equipment mainly includes three types: tank furnace, rotary kiln and rotary bed. Rotary kiln calcining petroleum coke has large production capacity, low investment, wide adaptability to raw materials, easy product quality control, and easy to realize automatic control of the production process. The purpose of calcining petroleum coke is to heat treat delayed petroleum coke to make it a qualified raw material for anode products. Petroleum coke is heated in the calcining kiln to discharge the volatile matter and moisture in it, thereby improving the density, mechanical strength, electrical conductivity and chemical stability of the carbonaceous raw materials. After calcining petroleum coke at 1200-1300℃, the true density is increased by about 30%. In order to improve the service life of the rotary kiln lining and to further reduce the heat dissipation on the kiln surface, the following measures are taken in the design of the rotary kiln.
(1) In order to improve the service life of the rotary kiln, the physical and chemical performance indicators of the rotary kiln calcined petroleum coke refractory bricks were formulated. From the indicators, it can be seen that the compressive strength of the materials used in the rotary kiln is 60% higher than that of ordinary refractory fire bricks; the change of the reburning line is increased from -1% to 0.02%; the refractoriness is increased from 1700℃ to 1790℃; the actual operation effect of the rotary kiln has increased the service life of the lining from one year in the past to more than two years at present.
(2) The structure of the refractory lining was redesigned. During the construction process of the old rotary kiln, the refractory bricks lining retained the construction joints along the length of the rotary kiln. This time, all the straight construction joints were changed to a maze structure of a snap-on type. Practice has proved that this structure solves the problem of premature damage to the castable insulation layer.
(3) In order to reduce the surface temperature of the kiln and reduce heat loss, the rotary kiln lining was specially optimized and designed, changing the previous "50mm light castable + 180mm heavy castable" to "70mm light castable + 200mm heavy castable", and the maximum surface temperature of the kiln body was reduced from 300℃ to 250℃, and the surface heat dissipation of the kiln body was reduced from 1.99×104kJ/m2.h to 1.5×104kJ/m2.h, a reduction of 24.6%. For the ash settling chamber, the previous "230mm light insulation brick + 230mm clay refractory brick" was changed to "75mm calcium silicate board + 50mm polycrystalline fiber board + 200mm clay castable". The surface temperature of the ash settling chamber was reduced from 150℃ to 90℃, and the surface heat dissipation of the ash settling chamber was reduced by 40%.
Using improved formula refractory bricks to build rotary kiln linings and adopting new and more reasonable structural forms during rotary kiln lining construction can significantly increase the service life of rotary kiln linings. Using the most optimized design method to determine the structural form of rotary kiln linings and settling chamber linings can further reduce the surface temperature of the kiln body, improve the working environment and significantly reduce surface heat dissipation losses.
